/**
 * @param {String} className
 * @param {String/Function} superCls
 * @param {Function} classImp
 */
function $class(className, superCls, classImp){
	if(superCls === '') superCls = Object;
	function clazz(){
		if(typeof this.init == "function"){
			this.init.apply(this, arguments);
		}
	}
	var p = clazz.prototype = new superCls();
	var _super = superCls.prototype;
	window[className] = clazz;
	classImp.apply(p, [_super]);
}

/**
 * 父类 Person
 */
$class('Person','',function(){
	// 私有属性age
	var age;
	this.init = function(n, a){
		// 公有属性name
		this.name = n;
		// 私有属性初始化
		age = a;
	};
	this.getName = function(){
		return this.name;
	};
	this.setName = function(name){
		this.name = name;
	}
	this.getAge = function(){
		return age;
	};
	this.setAge = function(a){
		age = a;
	};
});

$class("Man",Person, function(supr){
	var school;
	this.init = function(n, a, s){
		supr.init.apply(this, [n,a]);
		school = s;
	}
	this.getSchool = function(){
		return school;
	};
	this.setSchool = function(s){
		school = s;
	};
});

var m = new Man('tom', 25, 'pku');
console.log(m.name); // tom 继承父类的共有属性name可以直接使用点操作符获取
console.log(m.age);  // undefined 父类的私有属性age不能直接使用点操作符获取
console.log(m.getAge()); // 25 可通过父类的共有方法getAge获取私有属性age
console.log(m.school); // undefined Man自己的私有属性仍然不能通过点操作符获取
console.log(m.getSchool()); // pku 通过getSchool()方法获取私有属性school
